The present invention relates to a hydraulic installation in a boat hull, comprising a hydraulic circuit with pump means, pressure medium-actuated operating means, control valve means for controlling the flow between the pump means and the pressure-actuated operating means, and cooling means for cooling the pressure medium in the hydraulic circuit
The invention also relates to a boat propeller drive, comprising a shell intended to be permanently mounted against a boat transom, a propeller rig mounted in the shell for pivoting about a steering axis, at least one pressure medium-actuated piston-cylinder device, by means of which the propeller rig is pivotable about the steering axis, and a control valve for controlling the pressure medium flow to and from the cylinder of the piston-cylinder device.
In most hydraulic installations of the type described above, some form of cooling arrangement is required to prevent overheating of the pressure medium. Usually, a separate heat exchanger is used in the hydraulic circuit. The purpose of the present invention is, in a hydraulic installation of the type described by way of introduction, to make it possible to achieve satisfactory cooling of the pressure medium without using a separate heat exchanger only intended for cooling purposes.
This is achieved according to the invention by virtue of the fact that the control valve means comprise at least one control valve with a valve housing, which is so fixed relative to the boat hull, that at least a portion of the valve housing is exposed to the hull surroundings, to thereby serve as cooling means for the pressure medium in the hydraulic circuit.
By placing the valve housing so that its outside is subjected to water spray during driving, it can assume the function of a conventional separate cooler, meaning that a separate cooler can be eliminated without having to add a new component to the hydraulic circuit.
In a boat propeller drive of the above described type, particular advantages are achieved if the control valve has a valve housing which is so arranged on the shell that at least a portion of the valve housing is exposed towards the propeller rig.
The control valve can then be delivered as a portion integrated into the propeller drive with pre-installed hydraulic lines between the valve and the steering cylinder(s) of the rig. No after-mounting of the control valve is required, and by virtue of the fact that the valve is exposed towards the propeller rig, it will automatically be subjected to water spray when the boat is driven. In a preferred embodiment of the propeller drive according to the invention, the valve housing is sealingly fixed in a through-opening in the shell. In this case it is sufficient to connect the lines from the inboard-mounted pump devices to the valve housing connections on the inside of the shell. No lines need be drawn through the shell or the transom of the hull.